Nepskoeite
A valid IMA mineral species
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About Nepskoeite
Formula:
Mg4Cl(OH)7 · 6H2O
Colour:
Colourless with a bright yellow tint.
Lustre:
Pearly
Hardness:
1½ - 2
Specific Gravity:
1.76
Crystal System:
Orthorhombic
Name:
Named after the Nepskoye potash/salt deposit, the type locality.
This page provides mineralogical data about Nepskoeite.
Unique Identifiers
Mindat ID:
7189
Long-form identifier:
mindat:1:1:7189:1
IMA Classification of Nepskoeite
Approved
IMA Formula:
Mg4Cl(OH)7·6H2O
Approval year:
1996
First published:
1998
Classification of Nepskoeite
3.BD.20
3 : HALIDES
B : Simple halides, with H2O
D : Simple halides with H2O and additional OH
3 : HALIDES
B : Simple halides, with H2O
D : Simple halides with H2O and additional OH
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Nep | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Nepskoeite
Pearly
Transparency:
Translucent
Colour:
Colourless with a bright yellow tint.
Streak:
White
Hardness:
1½ - 2 on Mohs scale
Density:
1.76(2) g/cm3 (Measured) 1.756 g/cm3 (Calculated)
Optical Data of Nepskoeite
Type:
Biaxial (-)
RI values:
nα = 1.532(2) nβ = 1.562(2) nγ = 1.562(2)
2V:
Measured: 5°
Max. Birefringence:
δ = 0.030
Based on recorded range of RI values above.
Based on recorded range of RI values above.
Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
Surface Relief:
Moderate
Dispersion:
weak
Optical Extinction:
Straight extinction, negative elongation
Chemistry of Nepskoeite
Mindat Formula:
Mg4Cl(OH)7 · 6H2O
Element Weights:
Elements listed:
Crystallography of Nepskoeite
Crystal System:
Orthorhombic
Cell Parameters:
a = 11.215(9) Å, b = 3.124(3) Å, c = 19.21(3) Å
Ratio:
a:b:c = 3.59 : 1 : 6.149
Unit Cell V:
673.04 ų (Calculated from Unit Cell)
Z:
2
Comment:
space group Pcmm, Pcm21 or Pc2m
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 11.41 Å | (29) |
| 9.78 Å | (46) |
| 9.60 Å | (38) |
| 4.25 Å | (20) |
| 3.498 Å | (100) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 25 : Evaporites (prebiotic) |
Type Occurrence of Nepskoeite
General Appearance of Type Material:
Occurs as 0.5–1.5 mm spherulites consisting of 0.5–1.0 mm fibers.
Place of Conservation of Type Material:
A. E. Fersman Mineralogical Museum, Moscow, Russia.
Associated Minerals at Type Locality:
Synonyms of Nepskoeite
Other Language Names for Nepskoeite
Related Minerals - Strunz-mindat Grouping
| 3.BD.05 | Cadwaladerite | Al5(H2O)3(OH)12 · n(Cl,H2O) |
| 3.BD.15 | Korshunovskite | Mg2Cl(OH)3 · 4H2O |
| 3.BD.25 | Koenenite | Na4Mg9Al4Cl12(OH)22 |
Other Information
IR Spectrum:
Bands at 3623, 3373, 1609, 1297, 1160 (weak), 733, and 591 cm–1.
Thermal Behaviour:
TG analysis: gradual weight loss (42.73 wt% at 900 °C)
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for Nepskoeite
mindat.org URL:
https://www.mindat.org/min-7189.html
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Please feel free to link to this page.
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References for Nepskoeite
Localities for Nepskoeite
Showing 1 localities.
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and further information on this occurrence.
? - Indicates mineral may be doubtful at this locality.
- Good crystals or important locality for species.
- World class for species or very significant.
(TL) - Type Locality for a valid mineral species.
(FRL) - First Recorded Locality for everything else (eg varieties).
All localities listed without proper references should be considered as questionable.
Russia (TL) | |
| Apollonov (1998) +1 other reference |
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Nepskoe K salt deposit, Nepa River basin, Lower Tunguska, Irkutsk Oblast, Russia